The verification of fingerprint has become an important way in the identification of a person. With the help of the computerized fingerprint verification technology, a great number of persons may be identified within a short time. In order to verify fingerprints in the computer system, an image input device is provided to input digitized images of fingerprints to the computer system. In the conventional art, input devices for fingerprint images included: dot scanner, line scanner, LCD camera, CMOS sensor, chip fingerprint sensor etc. Digitized images input by these input devices may be stored in the memory devices of a computer system for further processing, such as matching with an enrolled fingerprint data file.
The verification of a fingerprint pertains to matching the fingerprint with an enrolled fingerprint. In the known art, the object to be matched is a data file representing a fingerprint. If the data file to be matched is the fingerprint image itself, the file contains data representing black-and-white or gray leveled image data of a fingerprint, within a predetermined area. In the file, the lines and the grooves of the fingerprint are represented by pixels with different gray levels respectively. Addresses of the pixels are represented by their respective rectangular coordinates. In other approaches, in the data file stored are equations representing curved lines of a fingerprint or coordinates of feature points of a fingerprint.
Fingerprint verification systems that are already made available to the world are developed on their respective platforms. Among them, each system has its particular way of verification and matching. Requirements and specifications of fingerprint images or fingerprint data are different from system to system. Generally speaking, verification of total image file of fingerprints is the most basic but time consuming approach. This approach is not used in any commercially available system. A standard approach of verification is the matching of feature points of fingerprints. Fingerprint verification system developed based on such an approach is relatively practicable. In addition, verification of fingerprints according to distribution of feature points, referenced by other features of the fingerprint, was disclosed by some inventors. Verification of fingerprints according to the similarity of curved lines of the fingerprint has also been suggested. No matter how a fingerprint is verified, the fingerprint image shall be pre-processed to comply with the requirements of the verification after it is input to the verification system through a fingerprint image input device. This step is after all necessary in every fingerprint verification system.
Due to the differences in the specification and requirements of fingerprint images for the fingerprint verification system, the design and specification of output data of their corresponding fingerprint image input devices are different from device to device. As described above, fingerprint image input devices used to input fingerprint images include: image sensor, line scanner, planar scanner, contact image sensor, CMOS sensor, chip sensor etc. Among them, image sensor, line scanner, planar scanner, CMOS sensor and contact image sensor are optical image input devices, in which the contact image sensor is a sensor where light source and image sensor are combined as one element. The chip sensor is an electronic sensor which, according to the distribution of capacitances and electric fields, obtains the topographic image data of a fingerprint. It is believed that other fingerprint image input devices may be developed, based on the above and other theories and used as input device for fingerprint in the near future.
In the existing and the future fingerprint image input devices, the differences in the required specification of the fingerprint image data rest in the resolution and the size of the input fingerprint image. The resolution of a fingerprint is represented by dpi (dot per inch), which indicates the most number of pixels existing within one inch. The resolution of the fingerprint image input devices includes 100, 200, 300, 400, 500, 600 and 1,000 or above. As to the size of the image, although most fingerprint image input devices provides a fingerprint image sized at 1 square inch, fingerprint images with greater or smaller sizes may also be provided. In addition, other features of the fingerprint data may also be required or provided. The above and other differences in requirements, specifications and features of the input fingerprint images make it difficult in the development of the fingerprint verification system.
The problems that have been discovered include that each type or model of the fingerprint image input devices needs a particular driving system. As a result, developers of fingerprint verification and application systems have to develop particular systems for respective fingerprint image input devices. From the viewpoint of the developers, such a requirement means a waste of resources.
In addition, as new fingerprint image input devices are developed, it is difficult for system developers to predict the specifications of future fingerprint image input devices. The fingerprint verification and application systems can only be applied in the existing fingerprint image input devices.
It is thus necessary to provide a control system for fingerprint image input device that may be applied to a variety of fingerprint image input devices.
It is also necessary to provide a novel control system for fingerprint image input device that may be applied to newly developed fingerprint image input devices.